• Microbiology and Biotechnology Letters
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• v.22 no.3
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• pp.252-258
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• 1994

Transglycosylation of stevioside in the attrition coupled heterogeneous reaction system using raw starch as a glycosyl donor has significant advantages over conventional reaction systems using liquefied starch as a donor. The transglycosylation of stevioside under the presence of organic solvent showed that transglycosylation reaction occurs via two steps ; initially from raw starch to cyclodextrin(CD), and then followed by transglycosylation of produced CD. Comparison of the transglycosylation efficiency of c$\alpha $-, $\beta $, $\gamma $-CDs indicated that $\alpha $-, $\beta $-CD are mainly utilized as a glycosyl donor for following reaction. The reaction mechanism of transglycosylation between stevioside and CD proceeded according to random sequential bireactant mechanism. The equilibrium constant of transglycosylation reaction of cyclodextrin glucanotransferase wase also evaluated. The structure of transglycosylated stevioside was confirmed by TLC, and it was found that glycosyl group(G$_{1}, $ ~ G$_{4}$-glycosidic bond.

• Bulletin of the Korean Chemical Society
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• v.26 no.5
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• pp.815-818
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• 2005

• KSBB Journal
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• v.9 no.2
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• pp.108-114
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• 1994

Kinetic equations for transglycosylation of stevioside in the attrition coupled reaction system using raw starch as a glycosyl donor were derived considering that the reaction was carried out through two steps; production of cyclodextrin(CD) from raw starch in the attrition coupled reaction system and then transglycosylation of glycosyl residues to stevioside from produced CD. Kinetic constants of derived equation were evaluated. The simulation result showed that the derived kinetic equations could predict the experimental data reasonably well and that can be utilized for optimization and scale-up of transglycosylation reactor and process developments.

• Bulletin of the Korean Chemical Society
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• v.25 no.1
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• pp.139-142
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• 2004

• Microbiology and Biotechnology Letters
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• v.26 no.2
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• pp.187-194
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• 1998

Glycosides were synthesized using transglycosylation reaction of amylase in water system. Starch as a glycosyl donor and benzylalcohol as an acceptor were selected as substrates of transglycosylation reaction. Among tested 9 commercial amylase, amyloglucosidase from Rhizopus sp. had high activity for transglycosylation from starch. The glycoside synthesized in water phase by amyloglucosidase was identified as benzylalcohol-${alpha}$-glucoside (BG) of which one molecule of benzylalcohol was bound to 1-OH of glucose. The transglycosylation reaction by amyloglucosidase were carried out in reaction system containing 50 mg starch, 50 mg benzylalcohol, and 10 units enzyme in pH 5.0 at 45$^{\circ}C$. The synthesized BG was hydrolyzed by ${alpha}$-glucosidase to produce glucose and benzylalcohol.

• Journal of Microbiology and Biotechnology
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• v.16 no.11
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• pp.1678-1683
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• 2006

A novel suspension-phase enzyme reaction system for the intermolecular transglycosylation of L-ascorbic acid into 2-O-${\alpha}$-D-glucopyranosyl L-ascorbic acid supplementing extrusion starch as the glycosyl donor was developed using cyclodextrin glucanotransferase from Thermoanaerobacter sp. A high conversion yield compared to the conventional soluble-phase enzyme reaction system using cyclodextrins and soluble starch was achieved. The optimal reaction conditions were 2,000 units of cycIodextrin glucanotransferase, 20 g/l of L-ascorbic acid, and 50 g/l of extrusion starch at $50^{\circ}C$ for 24 h. The new suspension-phase enzyme reaction system also exhibited several distinct advantages other than a high conversion yield, including a lower accumulation of oligosaccharides and easily separable residual extrusion starch by centrifugation or filtration in the reaction mixture, which will facilitate the purification of 2-O-${\alpha}$-D-glucopyranosyl L-ascorbic acid. The new suspension-phase enzyme reaction system seems to be potentially applicable as the industrial process for the production of thermally and oxidatively stable 2-O-${\alpha}$-D-glucopyranosyl L-ascorbic acid.

• Korean Journal of Microbiology
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• v.34 no.3
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• pp.137-143
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• 1998

Glycosides were synthesized using transglycosylation reaction of amylase in water system. The glycosides synthesized in water phase by a-amylase with starch as a glycosyl donor and benzylalcohol as an acceptor were identified as benzylalcohol-${\alpha}$-glucoside (BG) and benzylalcohol-${\alpha}$-maltoside (BM) of which one molecule of benzylalcohol was bound to 1-OH of glucose. The final products were BG in reaction system of pH 5.0, and BM in that of pH 8.0. The transglycosylation reaction by ${\alpha}$-amylase were carried out in water system containing 50 mg starch, 50 mg benzylalcohol, and 10 units enzyme at $30-35^{\circ}C$ for 3 days. The synthesized BG was hydrolyzed to glucose and benzylalcohol by ${\alpha}$-glucosidase, while ${\alpha}$-amylase hydrolyzed BM to glucose and benzylalcohol-${\alpha}$-glucoside in pH 5.0. Maltotriose resemble structurally to BM was rapidly hydrolyzed to glucose and maltose by ${\alpha}$-amylase at pH 5.0, being slightly hydrolyzed at pH 8.0, but not transglycosylated in present of benzylalcohol.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.3
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• pp.174-180
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• 2000

Cyclodextrin glucanotransferase (CGTasa) from Thermoanaerobacter sp. was adsorbed on the ion exchange resin Amberlite IRA-900. The optimum conditions for the immobilization of the CGTase were pH6.0 and 600 U CGTase/g resin, and the maximum yield of immobilization was around 63% on the basis of amount ratio of the adsorbed enzyme to intial amount in the solution. Immobilixation of CGTase shifted the optimum temperature for the enzyme to peoduce transglycosylated xylitol from 7$0^{\circ}C$ to 9$0^{\circ}C$ and improved the thermal stability of immobilized CGTase, especially after the addition of soluble starch and calcium ions. Transglycosylated xylitol was continuoncly produced using immobilized CGTase in the column type packed bed reactor, and the operating conditions for maximum yield were 10%(w/v) dextrin (13 of the dextrose equivalent) as the glycosyl donor, 10%(w/v) dextrin (13 of the dextrose equivalent) as the glycosyl donor, 10%(w/v) xylitor as the glycosyl acceptor, 20mL/h of medium fiow rate, and 6$0^{\circ}C$. The maximum yield of transglycosylated xylitol and productivity were 25% and 7.82 g.L-1.h-1, respectively. The half-life of the immobilized CGTase in a column type packed bed reactor was longer than 30 days.

• Bulletin of the Korean Chemical Society
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• v.16 no.7
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• pp.625-630
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• 1995

α-Linked D-altropyranosidic derivatives were obtained by configurational change at C-3 of α-D-mannopyranosides as the key step in preparation of allyl and methyl α-D-glycopyranosides of 6-deoxy-D-altro-heptose. The manno-altro conversion was effected by sequential reactions of Swern oxidation and stereoselective borohydride reduction. Allyl 4,6-O-benzylidene-2-O-p-methoxybenzyl-α-D-mannopyranoside was transformed to the corresponding altropyranoside via 3-oxo-arabino-hexopyranoside. Allyl 7-O-benzyl-6-deoxy-3,4-O-isopropylidene-α-D-altro-heptopyranoside has been prepared as a glycosyl acceptor to be coupled with β-D-GlcpNAc-(1→3)-α-D-Galp glycosyl donor for the synthesis of an O-antigen repeating unit of Campylobacter jejuni serotypes O:23 and O:36. Stereoselective borohydride reduction also succeeded in yielding methyl 2,4,7-tri-O-benzyl-6-deoxy-α-D-altro-heptopyranoside from the corresponding 3-oxo-α-D-arabino-heptopyranoside. C-6 Homologation was achieved by sequential reactions of cyanide displacement of 6-sulphonates, reduction of the resulting heptopyranosidurononitrile with diisobutylaluminum hydride, hydrolysis of the imine, and further reduction with sodium borohydride.

• Korean Journal of Microbiology
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• v.35 no.1
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• pp.1-6
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• 1999

Benzylalcohol-$\alpha$-glucoside (BG) was synthesized from soluble starch by transglycosylation of $\alpha$-amylase. Transglycosylation in water-organic two phase system containing 1% soluble starch as a glycosyl donor, 90% benzylalcohol as a glycosyl acceplor, 10% citrate buffer solulion (0.1 M, pH 5.0), and 10 unit of $\alpha$-amylase (Aspergilllw oryzae) was showed highcst efficiency. About 4 mg BG was obtained from 10 mg starch in reaction for 80 hrs at $40^{\circ}C$. Initially benzylalcohol-$\alpha$-maltoside Q3M) was major product, but as the reaction proceeded, it was hydrolyzed to glucose and BG. Finally the product of transglycosylation by $\alpha$-amylase was only BG. The both products did not show reducing powcr and hydrolyzed by $\alpha$-glucosidase and $\alpha$-amylase, respectively. The molecular wcights of both were estimated to be 270 and 432 by ES1-Mass, respectively.